The seaside community of Huntington Beach, California, was the scene of chaotic, violent, brawls as supporters and opponents of US President Donald Trump clashed, leading to four arrests.

Trump supporters were holding a rally Saturday in the popular southern Californian beach town when multiple fights broke out with demonstrators who had come to protest the event. The Los Angeles Times reported that the violence was sparked after one of the protesters pepper sprayed a woman who was one of the rally’s organizers. The OC register reports that 2,000 Trump supporters attended the rally. The fighting started early in the afternoon as the supporters of the president were marching along Bolsa Chica state beach around 40 miles (64 km) south of Los Angeles.

California State Parks Police estimated that 2,000 Trump supporters attended the rally. Approximately 20 anti-Trump protesters, dressed all in black, were at the scene. They reportedly refused to move from a bike path to allow the rally to pass and the confrontation quickly turned violent.

Footage from the scene shows people fighting in the sand and a group of nearly two dozen Trump supporters chasing a masked man away from the beach and onto a freeway. The man was then stopped by members of the California highway patrol.

“I hit him five times with the flag over his head,” Travis Guenther, who was carrying a “Make America Great Again” flag, boasted to the Los Angeles Times.

Four counter-protesters were arrested, three for illegal use of pepper spray and one for assault and battery, Kevin Pearsall, a spokesman for the California state parks police, said on to Reuters. None of their names were immediately released. Pearsall confirmed that at least one person was pepper-sprayed by an anti-Trump protester.

The Huntington Beach rally was part of wider pro-Trump rallies taking place across America. The demonstration in Omaha, Nebraska, also spiraled into violence as a fracas broke out between the president’s supporters and detractors. KETV Omaha report that eight people were arrested and police officers fired pepper balls to disperse the crowd.

On Saturday evening, Trump thanked those who attended the rallies to support him, saying on Twitter: “Thanks you for all of the Trump Rallies today. Amazing support. We will all MAKE AMERICA GREAT AGAIN!”